Computer trackball



FIG. 1 is a top perspective view of a computer trackball showing our new design;

FIG. 2 is a side perspective view thereof;

FIG. 3 is a right side elevational view thereof on an enlarged scale;

FIG. 4 is a bottom plan view thereof; and,

FIG. 5 is a rear elevational view thereof.

The partial broken line drawings of a cord in FIG. 1 and the keyboard in FIG. 2 are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a computer trackball, as shown and described. 